An innovative approach for detection of surface quality based on specific work environment using experiments, aerodynamic simulation, and theoretical analysis

Abstract

The surface quality of part using hydroforming process is superior to the surface quality of part using traditional stamping process, which is due to the fluid friction holding effect in the hydroforming process. In order to verify the point, a method for detecting the surface quality of parts based on the specific work environment has been proposed, which used the combination of the aerodynamic numerical simulation and theoretical analysis. The parts with the same dimensions were obtained by use of hydraulic bulge technology and traditional stamping process, the surfaces of the parts were scanned using laser tracker, and the measurement points were fitted to curved surfaces. According to four kinds of error values of fitting results, experimental procedure is judged to be accurate; the hydraulic bulge test and numerical simulation were carried out for the parts with different height to diameter ratio, and the finite element model is correct according to the distribution tendency of the wall thickness of the two measurement paths. The profile curves are fitted by using the 5° polynomial, and the curves are more accurate and passed through all the measurement points. The contour points along the diameter direction were fitted using the 5° polynomial, and then, the fitted curves were imported into FLUENT for simulation of transonic aerodynamic flow. According to the pressure distribution, velocity distribution, and the Mach number of flow field on the surface of parts, it is indicated that the surface quality of the parts using hydraulic bulge is better. Finally, the expressions of the third variable of the stress partial tensor for the two kinds of forming process were derived. Based on the different characterization parameters, the viewpoint above is further verified by the theory.